fix(TimetableController): update via-Fairmount trains

[thecristen]

Summary of changes

Asana Ticket: Timetable | Add "via Fairmount line" note to more Franklin/Foxboro trains

I basically followed the approach of this prior state of code. The "Via Fair- Mount Line" messages shows in the timetable for CR-Franklin for 4-5 trains in each direction, spanning 5 or 4 cells between Reading and Back Bay stations (the difference accounts for Hyde Park being omitted in one direction).

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General checks

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[kotva006]

Looks good 👍